Filter and modify list object using java 8 streams

Question

I'am using spring and I defined bean with ArrayList. invites it is a list with Invite objects.

@Getter
public class Invite {

    private String invitee;
    private String email;
    private boolean confirm;
    private String token;
}

This is my data privider class :

@Getter
public class InvitationsData {

    private List<Invite> invites = new ArrayList<>();

    @PostConstruct
    private void initInvites(){
        invites.add(new Invite("John", "[email protected]", false, "6456453"));
        invites.add(new Invite("John", "[email protected]", false, "3252352"));
    }
}

In configuration class I created @Bean from InvitationsData - it works.

In the service I would like to modify one object from list which matches to token string and have set confirm to false.

invitationsData.getInvites()
               .stream()
               .filter(i -> token.equals(i.getToken()))
               .filter(i -> !i.isConfirm())
               .forEach(i -> {
                   i.setConfirm(true);
               });

This stream works fine. Now, when someone call method twice for confirmed object I would like to throw CustomException. How can I do this with this stream? Where can I put orElseThrow?

EDIT:

My current solution. I use peek instead of forEach

invitationsData
                .getInvites()
                .stream()
                .filter(i -> token.equals(i.getToken()))
                .filter(i -> !i.isConfirm())
                .peek(i -> i.setConfirm(true))
                .findFirst()
                .orElseThrow(() -> new InvitationConfirmedException("Error"));

Is token unique or multiple Invite can have same ?

azro
– azro

2019-01-16 22:29:13 +00:00
Commented Jan 16, 2019 at 22:29 — azro
– azro, Commented Jan 16, 2019 at 22:29
you can put the check inside forEach

Adam Siemion
– Adam Siemion

2019-01-16 22:31:38 +00:00
Commented Jan 16, 2019 at 22:31 — Adam Siemion
– Adam Siemion, Commented Jan 16, 2019 at 22:31
@azro token is unique

lukassz
– lukassz

2019-01-16 22:50:19 +00:00
Commented Jan 16, 2019 at 22:50 — lukassz
– lukassz, Commented Jan 16, 2019 at 22:50

azro · Accepted Answer · 2019-01-16 22:35:39Z

3

If the token is unique you can do :

getInvites().stream()
            .filter(i -> token.equals(i.getToken()))
            .filter(i -> !i.isConfirm())
            .findAny()
            .orElseThrow(IllegalArgumentException::new)
            .setConfirm(true);

If not :

getInvites().stream()
            .filter(i -> token.equals(i.getToken()))
            .forEach(i -> {
                if (i.isConfirm()) 
                    throw new CustomException();
                else 
                    i.setConfirm(true);
            });

answered Jan 16, 2019 at 22:35

azro

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1 Comment

Kartik Over a year ago

the code for when the token is not unique, it will skip the other valid ones as soon as the exception is thrown.. unless it is caught right there in foreach

Bruno Holanda · Accepted Answer · 2023-07-06 10:45:06Z

0

Just adding to azro answer, for anyone who have a similar scenario, in case you're not sure if the object is on the list, and if it is ok for it not to be, you might prefer to not throw the exception if nothing is found. The code will be like:

getInvites().stream()
        .filter(i -> token.equals(i.getToken()))
        .filter(i -> !i.isConfirm())
        .findAny()
        .ifPresent(i -> i.setConfirm(true));

answered Jul 6, 2023 at 10:45

Bruno Holanda

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